It's not a big issue. HN users tend to upvote preferred sources, post cross-links, or discussions center around specifics in each article.
But it's also not optimal. Multiple articles on the same subject could benefit from a single discussion on the subject matter they have in common. Or compare article A versus article B's coverage. Also I suspect most HN users don't like laying out some argument & post, only to discover 10m later that same topic was argued to death in a related story. Or upvote a less-preferred source while a more-preferred source already saw lots of comments & upvotes.
It could (for example) be implemented by adding a poll to let HN users vote on what to use as primary link. Or just list the various links. Users can add candidates, select/upvote which they prefer, most popular one gets hugged, additional articles serve as extras. Hey this sounds a lot like a mini-election!
Edit: in effect, it would be a kind of grouping of articles under 1 heading.
Your thoughts & suggestions please?